The present invention relates to a joint unloading device and, more particularly, to a transcutaneous joint unloading device.
Joint replacement is one of the most common and successful operations in modern orthopaedic surgery. It consists of replacing painful, arthritic, worn or diseased parts of a joint with artificial surfaces shaped in such a way as to allow joint movement. Osteoarthritis is a common diagnosis leading to joint replacement. Such procedures are a last resort treatment as they are highly invasive and require substantial periods of recovery. Total joint replacement, also known as total joint arthroplasty, is a procedure in which all articular surfaces at a joint are replaced. This contrasts with hemiarthroplasty (half arthroplasty) in which only one bone's articular surface at a joint is replaced and unincompartmental arthroplasty in which the articular surfaces of only one of multiple compartments at a joint (such as the surfaces of the thigh and shin bones on just the inner side or just the outer side at the knee) are replaced. Arthroplasty as a general term, is an orthopaedic procedure which surgically alters the natural joint in some way. This includes procedures in which the arthritic or dysfunctional joint surface is replaced with something else, procedures which are undertaken to reshape or realigning the joint by osteotomy or some other procedure. As with joint replacement, these other arthroplasty procedures are also characterized by relatively long recovery times and are highly invasive procedures. A previously popular form of arthroplasty was interpositional arthroplasty in which the joint was surgically altered by insertion of some other tissue like skin, muscle or tendon within the articular space to keep inflammatory surfaces apart. Among other types of arthroplasty are resection(al) arthroplasty, resurfacing arthroplasty, excisional arthroplasty, mold arthroplasty, cup arthroplasty, silicone replacement arthroplasty, and osteotomy to affect joint alignment or restore or modify joint congruity. When it is successful, arthroplasty results in new joint surfaces which serve the same function in the joint as did the surfaces that were removed. Any chondrocytes (cells that control the creation and maintenance of articular joint surfaces), however, are either removed as part of the arthroplasty, or left to contend with the resulting joint anatomy. Because of this, none of these currently available therapies are chondro-protective.
Other approaches to treating osteoarthritis involve an analysis of loads which exist at a joint. Both cartilage and bone are living tissues that respond and adapt to the loads they experience. Within a nominal range of loading, bone and cartilage remain healthy and viable. If the load falls below the nominal range for extended periods of time, bone and cartilage can become softer and weaker (atrophy). If the load rises above the nominal level for extended periods of time, bone can become stiffer and stronger (hypertrophy). Finally, if the load rises too high, then abrupt failure of bone, cartilage and other tissues can result. Accordingly, it has been concluded that the treatment of osteoarthritis and other bone and cartilage conditions is severely hampered when a surgeon is not able to precisely control and prescribe the levels of joint load. Furthermore, bone healing research has shown that some mechanical stimulation can enhance the healing response and it is likely that the optimum regime for a cartilage/bone graft or construct will involve different levels of load over time, e.g. during a particular treatment schedule. Thus, there is a need for devices which facilitate the control of load on a joint undergoing treatment or therapy, to thereby enable use of the joint within a healthy loading zone.
Certain other approaches to treating osteoarthritis contemplate external devices such as braces or fixators which attempt to control the motion of the bones at a joint or apply cross-loads at a joint to shift load from one side of the joint to the other. A number of these approaches have had some success in alleviating pain but have ultimately been unsuccessful due to patient discomfort or the inability of the devices to facilitate and support the natural motion and function of the diseased joint.
One new approach to treating osteoarthritis involves implantation of an extra-articular implantable joint unloading device which is positioned alongside the painful joint and bears some of the load normally borne by the joint. This unloading device reduces pain by cushioning the joint from excessive loading. Since the device is extra-capsular and extra-articular, no bone, ligament, or cartilage is removed and future treatment options, such as joint replacement, are still available if needed. However, for some patients a more temporary solution may be more attractive. Patients and physicians may also be interested in providing an unloading device in which a portion of the device is external for ease of adjustment and removal.
With the foregoing applications in mind, it has been found to be desirable to develop temporary joint unloading structures for mounting to body anatomy with at least a portion of the unloading structure external and removable. Such structures should conform generally to body anatomy and cooperate with body anatomy to achieve desired load reduction, energy absorption, energy storage, and energy transfer. For these implant structures to function optimally, they must not cause an adverse disturbance to joint motion. Therefore, what is needed is an approach which addresses both joint movement and varying loads as well as complements underlying or adjacent anatomy.
Briefly and in general terms, the present disclosure is directed towards treating diseased or mal-aligned body joints, typically affected by osteoarthritis, using a transcutaneous joint unloading device without limiting the range of motion of the patient's articulating joint. The devices of the present invention accomplish one or more of: absorbing energy during normal gait, reducing load on at least a portion of the natural joint, load transferring or bypassing, energy cushioning, and load sharing, unloading or load redistribution. In addition, both energy dampening and shock absorption are considered in effecting such load manipulations. Further, the particular anatomy of a patient is considered in the contemplated approaches in that loads on desired portions of anatomy are manipulated without overloading healthy surfaces. In a preferred aspect, the present invention adds an energy absorber to the joint to reduce energy transferred through the natural joint. One aspect includes a system for manipulating or absorbing energy transferred by members defining a joint.
According to an aspect of the present invention, a transcutaneous unloading device for a joint comprises a load absorber having a first and a second mating portion, a load absorbing portion disposed between the first and the second mating portions, and the load absorbing portion comprising a single load absorbing pivot, a first percutaneous anchor having a first anchor portion configured to be affixed to a first member of the joint, and a first anchor mating portion for mating with the first mating portion, and a second percutaneous anchor having a second anchor portion configured to be affixed to a second member of the joint, and a second anchor mating portion for mating with the second mating portion, wherein the first and second mating portions and the first and second anchors are configured so that the load absorbing portion is disposed externally of a user's skin and so that the load absorbing pivot is pivotable at least about an axis substantially aligned with an axis of rotation of the first and second members of the joint.
According to another aspect of the present invention, a method of treating a joint comprises attaching a first anchor portion of a first percutaneous anchor to a first member of the joint, attaching a second anchor portion of a second percutaneous anchor to a second member of the joint, and attaching a load absorber to the first and second anchors so that a load absorbing portion of the load absorber is disposed externally of a user's skin by attaching a first and a second mating portion of the load absorber to first and second anchor mating portions of the first and second anchors, the load absorbing portion being disposed between the first and the second mating portions, the load absorbing portion comprising a single load absorbing pivot, the load absorber being attached so that the load absorbing pivot is pivotable at least about an axis substantially aligned with an axis of rotation of the first and second members of the joint.
According to another aspect of the present invention, a transcutaneous unloading device for a joint comprises a load absorber having a first and a second mating portion and a load absorbing portion disposed between the first and the second mating portions, a first percutaneous anchor having, at a first end thereof, a first anchor portion configured to be affixed to a first member of the joint, and, at a second end thereof, a first anchor mating portion for mating with the first mating portion, and a second percutaneous anchor having, at a first end thereof, a second anchor portion configured to be affixed to a second member of the joint, and, at a second end thereof, a second anchor mating portion for mating with the second mating portion, wherein the first and second mating portions and the first and second anchors are configured so that the load absorbing portion is disposed externally of a user's skin, and first ends of the first and second anchors are disposed on opposite ends of the first and second anchors from the second ends of the first and second anchors and are configured to be disposed subcutaneously.
According to another aspect of the present invention, a method of treating a joint, comprises attaching a first anchor portion at a first end of a first percutaneous anchor to a first member of the joint, attaching a second anchor portion at a first end of a second percutaneous anchor to a second member of the joint, and attaching a load absorber to the first and second anchors so that a load absorbing portion of the load absorber is disposed externally of a user's skin by attaching a first and a second mating portion of the load absorber to first and second anchor mating portions of the first and second anchors at second ends of the first and second anchors opposite the first ends of the first and second anchors, the load absorbing portion being disposed between the first and the second mating portions, and the first ends of the first and second anchors being disposed subcutaneously.
According to another aspect of the present invention, a transcutaneous unloading device for a joint comprises a single load absorber having a first and a second mating portion and a load absorbing portion disposed between the first and the second mating portions, a first percutaneous anchor having a first anchor portion configured to be affixed to a first member of the joint, and a first anchor mating portion for mating with the first mating portion, and a second percutaneous anchor having a second anchor portion configured to be affixed to a second member of the joint, and a second anchor mating portion for mating with the second mating portion, wherein the first and second mating portions and the first and second anchors are configured so that the load absorbing portion is disposed externally of a user's skin only on one side of the joint.
According to another aspect of the present invention, a method of treating a joint comprises attaching a first anchor portion of a first percutaneous anchor to a first member of the joint, attaching a second anchor portion of a second percutaneous anchor to a second member of the joint, and attaching a single load absorber to the first and second anchors so that a load absorbing portion of the load absorber is disposed externally of a user's skin only on one side of the joint by attaching a first and a second mating portion of the load absorber to first and second anchor mating portions of the first and second anchors, the load absorbing portion disposed between the first and the second mating portions.
According to another aspect of the present invention, a transcutaneous unloading device for a joint comprises a load absorber having a first and a second mating portion and a load absorbing portion disposed between the first and the second mating portions, a first percutaneous anchor having a first anchor portion configured to be affixed to a first member of the joint, and a first anchor mating portion for mating with the first mating portion, and a second percutaneous anchor having a second anchor portion configured to be affixed to a second member of the joint, and a second anchor mating portion for mating with the second mating portion, wherein the first and second mating portions and the first and second anchors are configured so that the load absorbing portion is disposed externally of a user's skin, and wherein the first and the second mating portions and the first and second anchor mating portions comprise quick-disconnect couplings.
According to another aspect of the present invention, a method of treating a joint comprises attaching a first anchor portion of a first percutaneous anchor to a first member of the joint, attaching a second anchor portion of a second percutaneous anchor to a second member of the joint, and attaching a load absorber to the first and second anchors so that a load absorbing portion of the load absorber is disposed externally of a user's skin by attaching a first and a second mating portion of the load absorber to first and second anchor mating portions of the first and second anchors, the load absorbing portion disposed between the first and the second mating portions, wherein the first and the second mating portions and the first and second anchor mating portions comprise quick-disconnect couplings.
According to another aspect of the present invention, a transcutaneous unloading device for a joint comprises a load absorber having a first and a second mating portion and a load absorbing portion disposed between the first and the second mating portions, a first percutaneous anchor having a first anchor portion configured to be affixed to a first member of the joint by at least one bone screw, and a first anchor mating portion for mating with the first mating portion, and a second percutaneous anchor having a second anchor portion configured to be affixed to a second member of the joint by one bone screw, and a second anchor mating portion for mating with the second mating portion, wherein the first and second mating portions and the first and second anchors are configured so that the load absorbing portion is disposed externally of a user's skin.
According to another aspect of the present invention, a method of treating a joint comprises attaching a first anchor portion of a first percutaneous anchor to a first member of the joint by at least one bone screw, attaching a second anchor portion of a second percutaneous anchor to a second member of the joint by one bone screw, and attaching a load absorber to the first and second anchors so that a load absorbing portion of the load absorber is disposed externally of a user's skin by attaching a first and a second mating portion of the load absorber to first and second anchor mating portions of the first and second anchors, the load absorbing portion disposed between the first and the second mating portions.
Other features of the unloading device and device will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the embodiments.